A continuing goal in the pavement-marking industry is to find economical products from which to form traffic-control stripes having a longer useful life than the commonly used painted stripes. The inability to satisfy this goal is indicated by the variety of products presently used to form stripes on a roadway:
One variety comprises paints based on epoxy resin, which provide longer life, but which nevertheless have achieved only a small usage, probably because their slow cure necessitates elaborate and expensive application procedures. Also, the applied lines tend to spall and crack, show little impact resistance, and discolor with age.
Thicker coatings, such as thermoplastic polymers extruded or sprayed while in a molten condition, have produced some increase in life because of the greater amount of material to be worn away. However, the increased amount of material also increases the cost of the markings, and expensive equipment and uncomfortably not procedures are required to apply them. Also, the high profile of these markings can be disturbing to passing traffic, and the lines are especially susceptible to removal by snowplow blades. The markings will also spall, especially from concrete, apparently because of the mismatch between the rigid thick markings and the concrete as to thermal expansion characteristics.
Preformed thick tapes of reduced elasticity have provided long useful life, but their cost has generally limited them to use in urban-type markings, such as short-distance lane striping, or stop bars or pedestrian lane markings at intersections, where heavy traffic, stop-start vehicle movements, and turning of vehicles inflicts severe stress.
Thinner preformed tapes have also been used, such as tapes comprising dead-soft aluminum foil carrying pigmented vinyl-based coatings in which glass microspheres or other particulate material is partially embedded. Such tapes are generally less expensive than the thicker preformed tapes described above, and their exceptional conformability assists in developing good adhesion to a roadway. However, these tapes are shorter-lived than the thicker preformed tapes, and their cost/life balance has generally limited them to specialized uses, such as temporary construction markings.
In sum, no presently used marking approach stands out as a superior-performance techhique, broadly suitable for large-scale marking such as down-the-road lane-striping on highways.